Medical image capturing apparatus

ABSTRACT

A CT apparatus includes a radiation source that emits radiation, a radiation detector that detects the radiation, an annular frame to which the radiation source and the radiation detector are attached and in which a subject is positioned in a bore, and three columns that hold the frame to be movable up and down in a vertical direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119 toJapanese Patent Application No. 2021-076586 filed on Apr. 28, 2021. Theabove application is hereby expressly incorporated by reference, in itsentirety, into the present application.

BACKGROUND 1. Technical Field

A technique of the present disclosure relates to a medical imagecapturing apparatus.

2. Description of the Related Art

For example, a medical image capturing apparatus, such as a computedtomography (CT) apparatus for imaging a subject in an upright posturedescribed in JP2017-077464A, has been suggested. The CT apparatusdescribed in JP2017-077464A comprises an imaging unit, and two columnsthat hold the imaging unit. The imaging unit is in an annular shape, andthe subject in the upright posture is positioned in a bore. The twocolumns are disposed in a front-rear direction of the subject. Thecolumns can expand and contract, and accordingly, a height position ofthe imaging unit can be changed.

The imaging unit includes a radiation source that emits radiation, aradiation detector that detects the radiation, and a frame. Theradiation source and the radiation detector are attached to the frame.The subject is irradiated with radiation from the radiation source ateach predetermined angle while rotating the frame, and radiationtransmitted through the subject is detected in the radiation detector,whereby a plurality of projection images are obtained. Then, a pluralityof projection images are reconstructed, and a tomographic image isobtained.

SUMMARY

In the CT apparatus described in JP2017-077464A, the number of columnsthat hold the imaging unit is two. For this reason, considering theinstallation stability or the like of the imaging unit, the columns areinevitably thick.

In the medical image capturing apparatus, such as the CT apparatusdescribed in JP2017-077464A, it is preferable that an operator, such asa radiographer, can visually recognize the subject from the outside ofthe medical image capturing apparatus in positioning the subject beforeimaging and during imaging. Note that, in a configuration in which thecolumns are inevitably thick as in JP2017-077464A, the subject is hardlyvisually recognized from the outside of the apparatus.

An embodiment according to the technique of the present disclosureprovides a medical image capturing apparatus that allows a subject to beeasily visually recognized from the outside compared to a case where thenumber of columns is two, such that the columns are inevitably thick.

A medical image capturing apparatus of the present disclosure comprisesa radiation source that emits radiation, a radiation detector thatdetects the radiation, an annular frame to which the radiation sourceand the radiation detector are attached and in which a subject ispositioned in a bore, and three or more columns that hold the frame tobe movable up and down in a vertical direction.

It is preferable that, in a case where the frame is viewed in plan viewand a polygon with the three or more columns as apexes is assumed, acenter of the frame falls within the polygon.

It is preferable that the frame has an annular shape, and the columnshold the frame to be rotatable around the subject.

It is preferable that the three or more columns are disposed at regularintervals on the same periphery.

It is preferable that, in a case where the columns are viewed from adirection in which the frame is viewed in plan view, the columns are inan arc shape following a shape of the frame.

It is preferable that at least one of the three or more columns has anopening for allowing the subject to be visually recognized from anoutside.

It is preferable that at least one of an input device or a display isattached to at least one of the three or more columns.

It is preferable that the column to which at least one of the inputdevice or the display is attached has rigidity higher than othercolumns.

It is preferable that the medical image capturing apparatus comprisesconnecting members that are connected to the frame at a first connectionposition and are connected to the columns at a second connectionposition, and the first connection position is higher than the secondconnection position.

It is preferable that both the radiation source and the radiationdetector protrude from any one of an upper edge or a lower edge of theframe.

It is preferable that the medical image capturing apparatus furtherincludes casters for transport.

It is preferable that the radiation source emits the radiation having apyramidal shape.

It is preferable that the subject is positioned in the bore in any oneof an upright posture or a sitting posture.

According to the technique of the present disclosure, it is possible toprovide a medical image capturing apparatus that allows the subject tobe easily visually recognized from the outside compared to a case wherethe number of columns is two, such that the columns are inevitablythick.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments according to the technique of the presentdisclosure will be described in detail based on the following figures,wherein:

FIG. 1 is a perspective view showing a CT apparatus;

FIG. 2 is a front view of an apparatus body of the CT apparatus;

FIG. 3 is a side view of the apparatus body of the CT apparatus;

FIG. 4 is a top view of the apparatus body of the CT apparatus;

FIG. 5 is a front view of the apparatus body of the CT apparatus showinga state in which a subject in a sitting posture on a wheelchair ispositioned;

FIG. 6 is a perspective view showing a radiation source, a radiationdetector, and radiation;

FIG. 7 is a diagram showing an elevation mechanism;

FIG. 8 is a diagram showing a rotation mechanism;

FIG. 9 is a block diagram showing a processing unit of a CPU of acontrol device;

FIG. 10 is a diagram showing an irradiation condition table;

FIG. 11 is a diagram showing a scene where the subject is led inside theapparatus body in a state in which a frame is at a retreat heightposition and a first rotation position;

FIG. 12 is a diagram showing a state in which the frame is rotated tothe first rotation position;

FIG. 13 is a diagram showing the outline of processing in a case wherean irradiation field confirmation instruction for confirming to anirradiation field of radiation is input;

FIG. 14 is a diagram showing the outline of processing in a case where ascout imaging instruction for performing scout imaging is input;

FIG. 15 is a diagram showing a state in which the frame is rotated to athird rotation position;

FIG. 16 is a diagram showing the outline of processing in a case where amain imaging instruction for main imaging is input;

FIG. 17 is a diagram showing a scene where the frame is rotated from afourth rotation position to a fifth rotation position;

FIG. 18 is a diagram showing the outline of processing in a case where areturn instruction for returning the frame to the retreat heightposition and the first rotation position is input;

FIG. 19 is a diagram showing a scene where the frame is returned fromthe fifth rotation position to the first rotation position;

FIG. 20 is a flowchart illustrating an imaging procedure of atomographic image by the CT apparatus;

FIG. 21 is a flowchart illustrating the imaging procedure of thetomographic image by the CT apparatus;

FIG. 22 is a flowchart illustrating the imaging procedure of thetomographic image by the CT apparatus;

FIG. 23 is a diagram showing another example of columns;

FIG. 24 is a diagram showing an aspect where the radiation source andthe radiation detector protrude from an upper edge of the frame;

FIG. 25 is a diagram showing the retreat height position and the firstrotation position in the aspect shown in FIG. 24;

FIG. 26 is a diagram showing another example of the first rotationposition;

FIG. 27 is a diagram showing an example of four columns;

FIG. 28 is a diagram showing an example of five columns;

FIG. 29 is a diagram showing an example of six columns; and

FIG. 30 is a diagram showing an elevation mechanism using acounterweight.

DETAILED DESCRIPTION

As shown in FIG. 1 as an example, a CT apparatus 10 is an apparatus thatobtains a tomographic image TI (see FIG. 16) of a subject S, and isconfigured of an apparatus body 11 and a control device 12. Theapparatus body 11 is installed, for example, in an imaging room of amedical facility. The control device 12 is installed, for example, in acontrol room next to the imaging room. The control device 12 is adesktop type personal computer, a notebook type personal computer, or atablet terminal. The CT apparatus 10 is an example of a “medical imagecapturing apparatus” according to the technique of the presentdisclosure.

As shown in FIGS. 1 to 4 as an example, the apparatus body 11 comprisesa stage 13, three columns 14A, 14B, and 14C, and a top plate 15. Thestage 13 is a flat plate having an octagonal shape. Casters 16 fortransport are attached to four corners of a back surface of the stage13.

The casters 16 comprise a rotation locking mechanism (not shown), andafter the apparatus body 11 is installed at an installation place, therotation of the casters 16 can be locked by operating the rotation lockmechanism. Alternatively, the casters 16 can be detached from the stage13, and after the apparatus body 11 is installed at the installationplace, the casters 16 can be detached. In a case where the frame 18 andthe like is viewed in plan view from above, and a quadrangle RAC (seeFIG. 1) with the four casters 16 as apexes is assumed, a center ofgravity CG (see FIG. 1) of the apparatus body 11 falls within thequadrangle RAC. The center of gravity CG is, for example, a center ofthe stage 13. For this reason, it is possible to stably transport theapparatus body 11. In a case of installing the apparatus body 11 withoutdetaching the casters 16, the installation stability of the apparatusbody 11 is increased.

The columns 14A to 14C have an appearance in a rectangular plate shape,and are provided upright at four corners of a front surface of the stage13. The columns 14A and 14C are disposed right and left on a frontsurface side of the apparatus body 11 (right and left in front of thesubject S). The column 14B is disposed at a center (behind the subjectS) on a back surface side of the apparatus body 11. The top plate 15 isattached to upper end portions of the columns 14A to 14C. The top plate15 has an appearance in an octagonal shape following the stage 13. Thetop plate 15 has a C shape in which a center portion is hollowed in acircular shape and a portion on the front surface side of the apparatusbody 11 between the columns 14A and 14C is notched. In the followingdescription, in a case where there is no need for particulardistinction, the columns 14A to 14C are collectively described as thecolumns 14.

A connecting member 17A is connected to the column 14A, a connectingmember 17B is connected to the column 14B, and a connecting member 17Cis connected to the column 14C. A frame 18 is connected to theconnecting members 17A to 17C. That is, the columns 14A to 14C and theframe 18 are connected through the connecting members 17A to 17C. In thefollowing description, in a case where there is no need for particulardistinction, the connecting members 17A to 17C are collectivelydescribed as the connecting members 17.

The frame 18 has an annular shape. The subject S is positioned at aposition of a center C (see FIG. 4) of a bore 19 of the annular frame18. In FIGS. 1 to 4, a scene where the subject S in an upright posturewith both hands up over a head is positioned is shown.

The columns 14 are provided with guide rails (not shown) that are fittedto the connecting members 17. The connecting members 17 and the frame 18can move up and down in a vertical direction along the guide rails. Thatis, the columns 14 hold the frame 18 to be movable up and down in thevertical direction. The frame 18 can rotate around the subject S withthe center C as a center axis. That is, the columns 14A to 14C hold theframe 18 to be rotatable around the subject S. The columns 14 may expandand contract to change a height position of the frame 18.

A radiation source 20 that emits radiation R (see FIG. 6), such asX-rays or γ-rays, and a radiation detector 21 that detects the radiationR are attached to the frame 18. The radiation source 20 and theradiation detector 21 are disposed at facing positions (positions at aninterval of 180°) of the frame 18. The radiation source 20 has a boxshape, and the radiation detector 21 has a pad shape. In a case wherethe frame 18 and the like are viewed in a direction in plan view fromabove, the radiation detector 21 has an arc shape following the shape ofthe frame 18. The frame 18 has a width W1 smaller than a width (here, awidth of the radiation detector 21 in a height direction greater thanthe radiation source 20) W2 of the radiation source 20 and the radiationdetector 21 in a height direction over a whole periphery (see FIG. 2).Both the radiation source 20 and the radiation detector 21 protrude froma lower edge of the frame 18.

A screw shaft 22A is provided in the column 14A, a screw shaft 22B isprovided in the column 14B, and a screw shaft 22C is provided in thecolumn 14C. The screw shafts 22A to 22C have a height from the stage 13to the top plate 15. The screw shafts 22A to 22C rotate, whereby theconnecting members 17A to 17C and the frame 18 move up and down in thevertical direction. In the following description, in a case where thereis no need for particular distinction, the screw shafts 22A to 22C arecollectively described as the screw shafts 22.

The column 14A has an opening 23A, the column 14B has an opening 23B,and the column 14C has an opening 23C. The openings 23A to 23C areformed by hollowing most of the columns 14A to 14C in a rectangularshape. It is possible to visually recognize the subject S from theoutside of the apparatus body 11 through the openings 23A to 23C. Sincethere are the openings 23A to 23C, each of the columns 14A to 14Cpartially looks like two parts; however, the two parts of each of thecolumns 14A to 14C are linked on the upper and lower sides of each ofthe openings 23A to 23C, and the number of parts is one. In thefollowing description, in a case where there is no need for particulardistinction, the openings 23A to 23C are collectively described as theopenings 23.

A touch panel display 25 is attached to the column 14A through a movablearm 24. The touch panel display 25 is operated by an operator of the CTapparatus 10, such as a radiographer. The touch panel display 25displays various kinds of information to the operator. The touch paneldisplay 25 is an example of “at least one of an input device or adisplay” according to the technique of the present disclosure. Thecolumn 14A is an example of “a column to which at least one of the inputdevice or the display is attached” according to the technique of thepresent disclosure.

An attachment portion 26 (see FIG. 4) of the column 14A for the movablearm 24 is thicker than other portions and rigidity is increased. Theattachment portion 26 is provided only in the column 14A, and is notprovided in the columns 14B and 14C. For this reason, the column 14A hasrigidity higher than the columns 14B and 14C.

In FIG. 4 in which the frame 18 and the like are viewed in plan viewfrom above, in a case where a position where there is the radiationsource 20 on the front surface of the apparatus body 11 is referred toas a position of 0°, the column 14A is disposed at a position of 60° ona circle CC centering on the center C of the frame 18, the column 14B isdisposed at a position of 180° on the circle CC, and the column 14C isdisposed at a position of 300° on the circle CC. That is, the columns14A to 14C are disposed at 120° intervals (at regular intervals on thesame periphery). In a case where a triangle TA (a regular triangleinscribed in the circle CC) with the columns 14A to 14C as apexes isassumed, the center C of the frame 18 falls within the triangle TA. Theangles of “0°”, “60°”, and the like indicate “0°”, “60°”, and the likein a meaning including an error that is generally allowed in thetechnical field to which the technique of the present disclosurebelongs, and an error to such an extent not contrary to the spirit andscope of the technique of that the present disclosure, in addition tocompletely “0°”, “60°”, and the like. The “regular intervals” indicateregular intervals in a meaning including an error that is generallyallowed in the technical field to which the technique of the presentdisclosure belongs, and an error to such an extent not contrary to thespirit and scope of the technique of that the present disclosure, inaddition to completely regular intervals.

In FIGS. 1 to 4, although an example where the subject S in the uprightposture with both hands up over the head is positioned in the bore 19has been shown, the technique of the present disclosure is not limitedthereto. As shown in FIG. 5 as an example, the CT apparatus 10 can alsoposition the subject S in a sitting posture on a wheelchair 30 in thebore 19 and image the subject S. Both the subject S in the uprightposture and the subject S in the sitting posture on the wheelchair 30are positioned such that a front surface thereof turns toward theposition of 0°.

As shown in FIG. 6 as an example, the radiation source 20 incorporates aradiation tube 35 and an irradiation field lamp 36. The radiation tube35 emits the radiation R. The irradiation field lamp 36 emits, forexample, orange visible light indicating an irradiation field of theradiation R.

The radiation source 20 has an irradiation field limiter 37. Theirradiation field limiter 37 is also referred to as a collimator anddefines the irradiation field of the radiation R to the radiationdetector 21. In the irradiation field limiter 37, an incidence openinginto which the radiation R from the radiation tube 35 is incident, andan emission opening from which the radiation R is emitted are formed.For example, four shielding plates are provided near the emissionopening. The shielding plates are formed of a material for shielding theradiation R, for example, lead. The shielding plates are disposed onsides of the quadrangles, in other words, are assembled in adouble-cross shape (checkered pattern), and forms an irradiation openingof the quadrangle that transmits the radiation R. The irradiation fieldlimiter 37 changes the size of the irradiation opening by changingpositions of the shielding plates, and with this, the irradiation fieldof the radiation R to the radiation detector 21 is changed. With theoperation of the irradiation field limiter 37, the radiation R in aquadrangular pyramidal shape is emitted from the radiation source 20. Aradiation angle θ of the radiation R is, for example, 45°.

The radiation detector 21 has, for example, a scintillator that convertsthe radiation R into visible light, a thin film transistor (TFT)substrate on which pixels for storing electric charge depending onvisible light converted from the radiation R are arranged in atwo-dimensional shape, and a signal processing circuit that outputs avoltage signal depending on electric charge as a projection image. Theradiation detector 21 may be of a type of directly detecting theradiation R instead of visible light converted from the radiation R.

As shown in FIG. 7 as an example, the elevation mechanism 40 that movesup and down the connecting member 17 and the frame 18 in the verticaldirection is a ball screw mechanism configured of the above-describedscrew shaft 22, a ball-containing nut 41 that is screwed with the screwshaft 22, a motor 42 for elevation that rotates the screw shaft 22, andthe like. The motor 42 for elevation is attached to the back surface ofthe stage 13. A height position of the frame 18 is derived from arotation orientation and a rotation speed of the motor 42 for elevation.

The connecting member 17 has a first connecting part 43 that isconnected to the frame 18, and a second connecting part 44 that isconnected to the column 14. The first connecting part 43 protrudes tothe frame 18 side, the second connecting part 44 protrudes to the column14 side, and the connecting member 17 has a Z shape as a whole. Thefirst connecting part 43 incorporates a bearing 45. The bearing 45 isfitted into a guide groove 46 (also set FIG. 1 and the like) formed overthe whole periphery of the frame 18. The bearing 45 rolls with therotation of the frame 18. The second connecting part 44 incorporates thenut 41.

A first connection position CP1 of the first connecting part 43 with theframe 18 is higher by a height H than a second connection position CP2of the second connecting part 44 with the column 14. Here, a point wherea center of the bearing 45 is in contact with the guide groove 46 of theframe 18 is set as the first connection position CP1. A point where acenter of the nut 41 is in contact with the screw shaft 22 is set as thesecond connection position CP2.

As shown in FIG. 8 as an example, a rotation mechanism 50 that rotatesthe frame 18 around the subject S is configured of a rotating belt 51that is stretched around the whole periphery of the frame 18, a motor 52for rotation, a potentiometer 53, and the like. The motor 52 forrotation is incorporated in the connecting member 17C and is connectedto a part of the rotating belt 51 led out from the frame 18 through apulley 54. With the drive of the motor for rotation 52, the frame 18rotates in a clockwise rotation (right-handed rotation) direction CW anda counterclockwise rotation (left-handed rotation) direction CCW. Thepotentiometer 53 is incorporated in the connecting member 17B and isconnected to a part of the rotating belt 51 led out from the frame 18through a pulley 55. The potentiometer 53 has a variable resistor aresistance value of which varies depending on the rotation position ofthe frame 18 and outputs a voltage signal depending on the rotationposition of the frame 18. The rotation position of the frame 18 isderived by the voltage signal from the potentiometer 53.

As shown in FIG. 9 as an example, a computer configuring the controldevice 12 comprises a storage 60, a memory 61, a central processing unit(CPU) 62, a display 63, an input device 64, and the like.

The storage 60 is a hard disk drive that is incorporated in the computerconfiguring the control device 12 or is connected to the computerthrough a cable or a network. Otherwise, the storage 60 is a disk arrayin which a plurality of hard disk drives are mounted in rows. In thestorage 60, a control program, such as an operating system, variousapplication programs, and various kinds of data accompanied with suchprograms, and the like are stored. A solid state drive may be usedinstead of the hard disk drive.

The memory 61 is a work memory on which the CPU 62 executes processing.The CPU 62 loads the programs stored in the storage 60 to the memory 61and executes processing depending on the programs. With this, the CPU 62integrally controls each unit of the computer. The memory 61 may beincorporated in the CPU 62.

The display 63 displays various screens. Various screens are providedwith an operation function by a graphical user interface (GUI). Thecomputer configuring the control device 12 receives an input of anoperation instruction from the input device 64 through various screens.The input device 64 is a keyboard, a mouse, a touch panel, a microphonefor voice input, and the like.

An operation program 70 is stored in the storage 60. The operationprogram 70 is an application program that causes the computer tofunction as the control device 12. In the storage 60, in addition to theoperation program 70, an irradiation condition table 71, order-specificirradiation condition information 72, and the like are stored.

In a case where the operation program 70 is started, the CPU 62 of thecontrol device 12 functions as a reception unit 75, a read write(hereinafter, abbreviated as RW) controller 76, an imaging controller77, an image processing unit 78, and a display controller 79 incooperation with the memory 61 and the like.

The reception unit 75 receives various operation instructions input fromthe operator through the touch panel display 25 and the apparatus body11 and the input device 64. For example, the reception unit 75 receivesan imaging menu 85. The reception unit 75 outputs the imaging menu 85 tothe RW controller 76.

The RW controller 76 receives the imaging menu 85 from the receptionunit 75. The RW controller 76 reads out an irradiation condition 86 ofthe radiation R corresponding to the received imaging menu 85 from theirradiation condition table 71. The RW controller 76 writes theirradiation condition 86 read out from the irradiation condition table71 to the order-specific irradiation condition information 72.

The imaging controller 77 controls the operations of the radiationsource 20 (radiation tube 35, irradiation field lamp 36, and irradiationfield limiter 37), the elevation mechanism 40 (motor 42 for elevation),the rotation mechanism 50 (motor 52 for rotation and potentiometer 53),and the radiation detector 21. The imaging controller 77 reads out theirradiation condition 86 from the order-specific irradiation conditioninformation 72. The imaging controller 77 drives the irradiation fieldlimiter 37 depending on the irradiation condition 86 and adjusts theirradiation field. The imaging controller 77 drives the radiation tube35 depending on the irradiation condition 86 and causes the emission ofthe radiation R from the radiation tube 35. The imaging controller 77outputs a projection image detected in the radiation detector 21 withthe irradiation of the radiation R from the radiation detector 21 to theimage processing unit 78.

The image processing unit 78 receives the projection image from theradiation detector 21. The image processing unit 78 executes variouskinds of image processing on the projection image. The image processingunit 78 executes reconstruction processing on a plurality of projectionimages after the image processing and generates a tomographic image TI.The image processing unit 78 outputs the projection images after theimage processing or the tomographic image TI to the display controller79.

The display controller 79 controls display of various kinds ofinformation on the touch panel display 25 and the display 63. Thedisplay controller 79 receives the projection images or the tomographicimage TI from the image processing unit 78. The display controller 79displays the projection images or the tomographic image TI on the touchpanel display 25 and the display 63.

The imaging menu 85 includes, for example, imaging order identificationdata (ID) and an imaging procedure (see FIG. 10). The imaging order IDis identification information of an imaging order issued by a physicianwho performs a medical examination using a tomographic image. Theimaging procedure is configured of a posture of the subject S, such asupright and sitting, an imaging part, such as a head, a neck, and aspine, and an attribute of the subject S, such as an adult male and anadult female.

The imaging order is transmitted from a radiology information system(RIS) (not shown) to the control device 12. The control device 12displays a list of imaging orders on the display 63 under the control ofthe display controller 79. The operator views the list of imaging ordersto confirm the contents. Subsequently, the control device 12 displays animaging menu corresponding to the imaging order on the display 63 in asettable form. The operator selects and inputs the imaging menudepending on the imaging order by operating the input device 64.

As shown in FIG. 10 as an example, the irradiation condition 86 isregistered in the irradiation condition table 71 for each imagingprocedure. In the irradiation condition 86, a tube voltage and a tubecurrent that are applied to the radiation tube 35, and an irradiationtime of the radiation R are included. Though not shown, a size of theirradiation field is also included in the irradiation condition 86. Theirradiation condition 86 can be subjected to fine adjustment with thehand of the operator. Instead of the tube current and the irradiationtime, a tube current-irradiation time product, called a mAs value, maybe used as the irradiation condition 86.

In the irradiation condition table 71, a scout imaging position and afourth rotation position are also registered for each imaging procedure.The scout imaging position is a set of a reference height position and asecond or third rotation position of the frame 18 in scout imaging. Thereference height position indicates the height of the frame 18 in a casewhere the front surface of the stage 13 is set to 0 cm. The secondrotation position is a position where the radiation source 20 confrontsthe subject S, that is, a position of 0°. The third rotation position isa position where the radiation source 20 faces a right side surface ofthe subject S, that is, a position of 90°. A position of 270° where theradiation source 20 faces the left side surface of the subject S may beset as the third rotation position.

Here, scout imaging is preliminary radiography that is performed toconfirm positioning of the subject S before main imaging for capturing aplurality of projection images of each predetermined angle to generatethe tomographic image TI. In scout imaging, after the frame 18 is at thereference height position and the second rotation position or the thirdrotation position, the irradiation of the radiation R with a dose lowerthan main imaging is performed to obtain one projection image.Hereinafter, the projection image obtained by scout imaging is describedas a scout image SI (see FIG. 14).

The imaging procedure includes an imaging procedure in which only thesecond rotation position is registered and an imaging procedure in whichboth the second rotation position and the third rotation position areregistered. For example, in an imaging procedure of “upright head adultmale”, only the second rotation position is registered. On the otherhand, for example, in an imaging procedure of “sitting spine adultmale”, both the second rotation position and the third rotation positionare registered.

The fourth rotation position is a rotation start position of the frame18 in main imaging. For example, in an imaging procedure of “uprighthead adult male”, the position of 0° is registered as the fourthrotation position. For example, in an imaging procedure of “sittingspine adult male”, the position of 90° is registered as the fourthrotation position.

Though not shown, in the order-specific irradiation conditioninformation 72, the irradiation condition 86, the scout imagingposition, and the fourth rotation position are registered for eachimaging order ID. The imaging controller 77 reads out the irradiationcondition 86, the scout imaging position, and the fourth rotationposition corresponding to a next imaging order ID from theorder-specific irradiation condition information 72 and controls theoperation of each unit depending on the read-out irradiation condition86, scout imaging position, and fourth rotation position.

As shown in FIG. 11 as an example, in leading the subject S inside theapparatus body 11, the frame 18 is moved to the retreat height positionby the elevation mechanism 40 and is rotated to the first rotationposition by the rotation mechanism 50 under the control of the imagingcontroller 77. The retreat height position is set on an upper end sideof the column 14. In more detail, the retreat height position is aposition of a highest point in an elevation range of the frame 18. Inthe example, the position of the highest point in the elevation range ofthe frame 18 is a position of a substantially upper end of the column14, and is a position where the second connecting part 44 of theconnecting member 17 is in contact with the back surface of the topplate 15. Incidentally, a position of a lowest point in the elevationrange of the frame 18 is a position of a substantially lower end of thecolumn 14 and is a position where the second connecting part 44 is incontact with the front surface of the stage 13. The first rotationposition is a position of 60° where the entire radiation source 20overlaps the column 14A as also shown in FIG. 12 in which the state ofFIG. 11 is viewed from above. The operator leads the subject S insidethe apparatus body 11 in such a state with a space between the columns14A and 14C as an entrance and positions the subject S. An arrow shownin FIGS. 11 and 12 indicates a direction in which the subject S is ledinside the apparatus body 11.

As shown in FIG. 13 as an example, after positioning the subject Sinside the apparatus body 11, the operator stays in the installationplace of the apparatus body 11 and operates the touch panel display 25to input an irradiation field confirmation instruction 90 for confirmingthe irradiation field of the radiation R. The reception unit 75 receivesthe irradiation field confirmation instruction 90 and outputsinformation indicating the reception of the irradiation fieldconfirmation instruction 90 to the imaging controller 77. The imagingcontroller 77 outputs an irradiation field confirmation command 91depending on the irradiation field confirmation instruction 90 to theradiation source 20, the elevation mechanism 40, and the rotationmechanism 50.

The content of the irradiation field confirmation command 91 is that theframe 18 is moved to the reference height position and the frame 18 isrotated to the position of 0°. Furthermore, the content of theirradiation field confirmation command 91 is that the irradiation fieldlamp 36 is turned on at the reference height position and the positionof 0°. The elevation mechanism 40 drives the motors 42 for elevation torotate the screw shafts 22, thereby moving the frame 18 to the referenceheight position. The rotation mechanism 50 drives the motor 52 forrotation to rotate the rotating belt 51, thereby rotating the frame 18to the position of 0°. The radiation source 20 drives the irradiationfield limiter 37 to adjust the irradiation field to an irradiation fielddepending on the irradiation condition 86, and then, turns on theirradiation field lamp 36 to irradiate the irradiation field withvisible light.

The operator visually recognizes visible light from the irradiationfield lamp 36 and determines whether or not the height position of theframe 18 and the positioning of the subject S are appropriate forimaging. In a case where determination is made that the height positionof the frame 18 and the positioning of the subject S are not appropriatefor imaging, the operator operates the touch panel display 25 to adjustthe height position of the frame 18 or performs the positioning of thesubject S again. In a case where determination is made that the heightposition of the frame 18 and the positioning of the subject S areappropriate for imaging, the operator operates the touch panel display25 to input a turn-off instruction of the irradiation field lamp 36. Thereception unit 75 receives the turn-off instruction and outputsinformation indicating the reception of the turn-off instruction to theimaging controller 77. The imaging controller 77 turns off theirradiation field lamp 36 in response to the turn-off instruction.

As shown in FIG. 14 as an example, after confirming the irradiationfield of the radiation R, the operator moves to the installation placeto the control device 12 and operates the input device 64 to input ascout imaging instruction 95 for scout imaging. The reception unit 75receives the scout imaging instruction 95 and outputs informationindicating the reception of the scout imaging instruction 95 to theimaging controller 77. The imaging controller 77 outputs a scout imagingcommand 96 depending on the scout imaging instruction 95 to theradiation source 20, the radiation detector 21, and the rotationmechanism 50.

The content of the scout imaging command 96 is that the height positionis maintained in a state at the time of the confirmation of theirradiation field of the radiation R, and the frame 18 is rotated to thesecond rotation position and/or the third rotation position.Furthermore, the content of the scout imaging command 96 is that scoutimaging is performed at the second rotation position and/or the thirdrotation position. The rotation mechanism 50 drives the motor 52 forrotation to rotate the rotating belt 51, thereby rotating the frame 18to the second rotation position and/or the third rotation position. FIG.15 shows a state in which the frame 18 is rotated to the position of 90°as the third rotation position.

The radiation source 20 drives the radiation tube 35 to irradiate thesubject S with the radiation R for scout imaging. The radiation detector21 detects the radiation R transmitted through the subject S to obtain aprojection image. The radiation detector 21 outputs the projection imageto the image processing unit 78.

The image processing unit 78 executes various kinds of image processingon the projection image from the radiation detector 21 to generate ascout image SI. The image processing unit 78 outputs the scout image SIto the display controller 79. The display controller 79 displays thescout image SI on the touch panel display 25 and the display 63.

The operator views the scout image SI on the display 63 and determinesagain whether or not the height position of the frame 18 and thepositioning of the subject S are appropriate for imaging. In a casewhere determination is made that the height position of the frame 18 andthe positioning of the subject S are not appropriate for imaging withthe scout image SI, the operator returns to the installation place ofthe apparatus body 11, turns on the irradiation field lamp 36 again, andadjusts the height position of the frame 18 or performs the positioningof the subject S again.

As shown in FIG. 16 as an example, in a case where determination is madethat the height position of the frame 18 and the positioning of thesubject S are appropriate for imaging with the scout image SI, theoperator operates the input device 64 to input a main imaginginstruction 100 for main imaging. The reception unit 75 receives themain imaging instruction 100 and outputs information indicating thereception of the main imaging instruction 100 to the imaging controller77. The imaging controller 77 outputs a main imaging command 101depending on the main imaging instruction 100 to the radiation source20, the radiation detector 21, and the rotation mechanism 50.

The content of the main imaging command 101 is that the height positionis maintained in a state at the time of the end of scout imaging, theframe 18 is rotated to the fourth rotation position, and then, the frame18 is rotated to a fifth rotation position at a first set rotation speedset in advance in a counterclockwise rotation direction CCW.Furthermore, the content of the main imaging command 101 is that mainimaging is performed while the frame 18 is being rotated from the fourthrotation position to the fifth rotation position. The rotation mechanism50 drives the motor 52 for rotation to rotate the rotating belt 51,thereby first rotating the frame 18 to the fourth rotation position.Thereafter, the rotation mechanism 50 rotates the frame 18 to the fifthrotation position at the first set rotation speed in thecounterclockwise rotation direction CCW. The fifth rotation position isa position where the frame 18 is rotated by 225° from the fourthrotation position in the counterclockwise rotation direction CCW in theexample.

FIG. 17 shows a case where the fourth rotation position is the positionof 0°. In this case, the fifth rotation position is a position of 135°where the frame 18 is rotated by 225° from the position of 0° in thecounterclockwise rotation direction CCW. Though not shown, the fifthrotation position in a case where the fourth rotation position is 90° isa position of 225°, and the fifth rotation position in a case where thefourth rotation position is 180° is a position of 315°.

The radiation source 20 drives the radiation tube 35 at eachpredetermined angle to irradiate the subject S with the radiation R formain imaging depending on the irradiation condition 86 at eachpredetermined angle. The radiation detector 21 detects the radiation Rtransmitted through the subject S at each predetermined angle to obtaina plurality of projection images. The radiation detector 21 sequentiallyoutputs a plurality of projection images to the image processing unit78.

The image processing unit 78 executes reconstruction processing on aplurality of projection images from the radiation detector 21 togenerate a tomographic image TI. The image processing unit 78 outputsthe tomographic image TI to the display controller 79. The displaycontroller 79 displays the tomographic image TI on the touch paneldisplay 25 and the display 63.

The operator views the tomographic image TI on the display 63 anddetermines whether or not re-imaging of the tomographic image TI isrequired. In a case where determination is made that re-imaging of thetomographic image TI is required, the operator operates the input device64 to input the main imaging instruction 100 again.

As shown in FIG. 18 as an example, in a case where determination is madethat re-imaging of the tomographic image TI is not required, theoperator operates the input device 64 to input a return instruction 105for returning the frame 18 to the retreat height position and the firstrotation position. The reception unit 75 receives the return instruction105 and outputs information indicating the reception of the returninstruction 105 to the imaging controller 77. The imaging controller 77outputs a return command 106 depending on the return instruction 105 tothe elevation mechanism 40 and the rotation mechanism 50.

The content of the return command 106 is that the frame 18 is returnedto the retreat height position, and the frame 18 is returned from thefifth rotation position to the first rotation position at a second setrotation speed of a double speed of the first set rotation speed in aclockwise rotation direction CW. The elevation mechanism 40 drives themotors 42 for elevation to rotate the screw shafts 22, thereby returningthe frame 18 to the retreat height position. The rotation mechanism 50drives the motor 52 for rotation to rotate the rotating belt 51, therebyreturning the frame 18 from the fifth rotation position to the firstrotation position at the second set rotation speed in the clockwiserotation direction CW.

FIG. 19 shows a case where the fifth rotation position is the positionof 135°. In this case, the rotation mechanism 50 returns the frame 18from the position of 135° as the fifth rotation position to the positionof 60° as the first rotation position at the second set rotation speedin the clockwise rotation direction CW. After the frame 18 is returnedto the retreat height position, and the frame 18 is returned to thefirst rotation position, the operator retreats the subject S from theinside of the apparatus body 11.

Next, the operations of the above-described configuration will bedescribed referring to flowcharts shown in FIGS. 20 to 22 as an example.In a case where the operation program 70 is started, as shown in FIG. 9,the CPU 62 of the control device 12 functions as the reception unit 75,the RW controller 76, the imaging controller 77, the image processingunit 78, and the display controller 79.

First, as shown in FIGS. 11 and 12, in a state in which the frame 18 ismoved to the retreat height position, and the frame 18 is rotated to thefirst rotation position, the subject S is led inside the apparatus body11 by the operator (Step ST100). Then, the subject S is positioned bythe operator (Step ST110).

As shown in FIG. 13, after the positioning of the subject S, theoperator inputs the irradiation field confirmation instruction 90through the touch panel display 25. The irradiation field confirmationinstruction 90 is received in the reception unit 75 (in Step ST120,YES). With this, the irradiation field confirmation command 91 is outputfrom the imaging controller 77 to the radiation source 20 and the like(Step ST130).

The elevation mechanism 40 is operated by the irradiation fieldconfirmation command 91 and the frame 18 is moved to the referenceheight position. The rotation mechanism 50 is operated and the frame 18is rotated to the position of 0° (Step ST140). In addition, theirradiation field limiter 37 is driven to adjust the irradiation fieldto the irradiation field depending on the irradiation condition 86,then, the irradiation field lamp 36 is turned on, and the irradiationfield is irradiated with visible light (Step ST150).

The operator determines whether or not the height position of the frame18 and the positioning of the subject S are appropriate for imaging withreference to visible light from the irradiation field lamp 36. In a casewhere the height position of the frame 18 and the positioning of thesubject S are not appropriate for imaging, the operator adjusts theheight position of the frame 18 or performs the positioning of thesubject S again. In a case where the height position of the frame 18 andthe positioning of the subject S are appropriate for imaging, theoperator inputs the turn-off instruction of the irradiation field lamp36 through the touch panel display 25. The turn-off instruction isreceived in the reception unit 75 (in Step ST160, YES). Then, theimaging controller 77 turns off the irradiation field lamp 36 (StepST170).

As shown in FIG. 14, after the confirmation of the irradiation field ofthe radiation R, the operator inputs the scout imaging instruction 95through the input device 64. The scout imaging instruction 95 isreceived in the reception unit 75 (in Step ST180, YES). With this, thescout imaging command 96 is output from the imaging controller 77 to theradiation source 20 and the like (Step ST190).

As shown in FIG. 15, the rotation mechanism 50 is operated by the scoutimaging command 96, and the frame 18 is rotated to the second rotationposition and/or the third rotation position (Step ST200). In addition,the subject S is irradiated with the radiation R for scout imaging fromthe radiation tube 35, and the radiation detector 21 detects theradiation R transmitted through the subject S to obtain the projectionimage (Step ST210).

The projection image obtained in the radiation detector 21 is subjectedto various kinds of image processing in the image processing unit 78 andgenerates the scout image SI. The scout image SI is displayed on thetouch panel display 25 and the display 63 under the control of thedisplay controller 79 (Step ST220).

The operator determines again whether or not the height position of theframe 18 and the positioning of the subject S are appropriate forimaging with reference to the scout image SI. In a case where the heightposition of the frame 18 and the positioning of the subject S are notappropriate for imaging, the operator turns on the irradiation fieldlamp 36 again and adjusts the height position of the frame 18 orperforms the positioning of the subject S again.

In a case where the height position of the frame 18 and the positioningof the subject S are appropriate for imaging, as shown in FIG. 16, theoperator inputs the main imaging instruction 100 through the inputdevice 64. The main imaging instruction 100 is received in the receptionunit 75 (in Step ST230, YES). With this, the main imaging command 101 isoutput from the imaging controller 77 to the radiation source 20 and thelike (Step ST240).

As shown in FIG. 17, the rotation mechanism 50 is operated by the mainimaging command 101, and the frame 18 is first rotated to the fourthrotation position (Step ST250). Thereafter, the frame 18 is rotated tothe fifth rotation position at the first set rotation speed in thecounterclockwise rotation direction CCW. In the interim, the subject Sis irradiated with the radiation R for main imaging at eachpredetermined angle from the radiation tube 35, and the radiationdetector 21 detects the radiation R transmitted through the subject Seach time to obtain a plurality of projection images (Step ST260).

A plurality of projection images obtained in the radiation detector 21are subjected to the reconstruction processing in the image processingunit 78 to generate the tomographic image TI. The tomographic image TIis displayed on the touch panel display 25 and the display 63 under thecontrol of the display controller 79 (Step ST270).

The operator determines whether or not re-imaging of the tomographicimage TI is required. In a case where the operator determines thatre-imaging of the tomographic image TI is required (in Step ST280, YES),the operator re-inputs the main imaging instruction 100 through theinput device 64, and the process returns to the processing of StepST240.

In a case where the operator determines that re-imaging of thetomographic image TI is not required (in Step ST280, NO), as shown inFIG. 18, the operator inputs the return instruction 105 through theinput device 64. The return instruction 105 is received in the receptionunit 75 (in Step ST290, YES). With this, the return command 106 isoutput from the imaging controller 77 to the elevation mechanism 40 andthe like (Step ST300).

The elevation mechanism 40 is operated by the return command 106 and theframe 18 is returned to the retreat height position. As shown in FIG.19, the rotation mechanism 50 is operated and the frame 18 is returnedfrom the fifth rotation position to the first rotation position at thesecond set rotation speed of a double speed of the first set rotationspeed in the clockwise rotation direction CW (Step ST310). After theframe 18 is returned to the retreat height position, and the frame 18 isreturned to the first rotation position, the operator retreats thesubject S from the inside of the apparatus body 11 (Step ST320). Aseries of Steps ST100 to ST320 is repeatedly performed in a there is anext imaging order (in Step ST330, YES).

As described above, the CT apparatus 10 comprises the radiation source20 that emits the radiation R, the radiation detector 21 that detectsthe radiation R, the annular frame 18 to which the radiation source 20and the radiation detector 21 are attached and in which the subject S ispositioned in the bore 19, and the three columns 14A to 14C that holdthe frame 18 to be movable up and down in the vertical direction. Forthis reason, it is possible to make each column 14 thin compared to acase where the number of columns is two. Accordingly, it is possible toprovide the CT apparatus 10 that allows the subject S to be easilyvisually recognized from the outside compared to a case where the numberof columns is two, such that the columns are inevitably thick. Theoperator can easily perform the positioning of the subject S and canalso easily perform the safety confirmation of the subject S duringimaging. Furthermore, it is possible to reduce a floor occupation areaof the apparatus body 11 compared to a case where the number of columnsis two.

As shown in FIG. 4, in a case where the frame 18 is viewed in plan viewand the triangle TA with the three columns 14A to 14C as the apexes isassumed, the center C of the frame 18 falls within the triangle TA.

On the contrary, a case where the center C of the frame 18 does not fallwithin the triangle TA is a case of a cantilever type in which, forexample, the columns 14A and 14C are disposed on the back surface sidewith respect to the center C and no column is disposed on the frontsurface side with respect to the center C. In the case of the cantilevertype, since weight balance significantly collapses, the installationstability of the frame 18 is degraded. Accordingly, in the embodiment,the three columns 14A to 14C are disposed such that the center C of theframe 18 falls within the triangle TA with the three columns 14A to 14Cas the apexes. For this reason, it is possible to suppress degradationof the installation stability of the frame 18.

The frame 18 has an annular shape, and the columns 14A to 14C hold theframe 18 to be rotatable around the subject S. The rotating frame 18 isheld by the three columns 14A to 14C, whereby it is possible to allowthe subject S to be easily visually recognized from the outside and tomaintain the rotation stability of the frame 18, compared to a casewhere the number of columns is two.

In the case of the cantilever type, the rotation stability of the frame18 is also degraded. Then, degradation of the rotation stability of theframe 18 causes destabilization of a positional relationship between theradiation source 20 and the radiation detector 21 at each angle of mainimaging. Accordingly, blur occurs in the projection image obtained ateach angle, and as a result, the image quality of the tomographic imageTI is deteriorated. In contrast, in the embodiment, as described above,since the three columns 14A to 14C are disposed such that the center Cof the frame 18 falls within the triangle TA with the three columns 14Ato 14C as the apexes, it is possible to dispel a concern thatdegradation of the rotation stability of the frame 18 causesdeterioration of the image quality of the tomographic image TI.

As shown in FIG. 4, the three columns 14A to 14C are disposed at regularintervals on the same periphery. Since the weight of the frame 18 isapplied to the three columns 14A to 14C with the best balance, it ispossible to further increase the installation stability of the frame 18.

As shown in FIG. 1 and the like, the columns 14 have the openings 23 forallowing the subject S to be visually recognized from the outside. Forthis reason, it is possible to provide the CT apparatus 10 that allowsthe subject S to be more easily visually recognized from the outside.

Although an example where all the three columns 14A to 14C have theopenings 23A to 23C has been described, the technique of the presentdisclosure is not limited thereto. For example, only one column 14disposed beside the installation place of the control device 12 amongthe three columns 14A to 14C may have the opening 23. The opening is notlimited to the rectangular opening 23 that extends in a longitudinaldirection of the column 14 shown in the drawing. A plurality of circularopenings or a mesh-patterned opening may be provided.

As shown in FIG. 1 and the like, the touch panel display 25 is attachedto the column 14A through the movable arm 24. For this reason, theoperator can input various instructions, such as the irradiation fieldconfirmation instruction 90 or can view the scout image SI and thetomographic image TI in some cases at the installation place of theapparatus body 11, and it is possible to improve the convenience of theCT apparatus 10.

The technique of the present disclosure is not limited to the touchpanel display 25 in which the input device and the display are combined,and at least one of the input device or the display may be attached tothe column 14. The number of columns 14 to which at least one of theinput device or the display is attached may be two or more.

As shown in FIG. 4, the column 14A provides the attachment portion 26for the movable arm 24, and has rigidity higher than the columns 14B and14C. For this reason, it is possible to restrain deformation of thecolumn 14 a due to the weight of the touch panel display 25, and tostably hold the touch panel display 25. The column 14A may be formed ofa material having rigidity higher than the columns 14B and 14C.

As shown in FIG. 7, the CT apparatus 10 comprises the connecting member17 that is connected to the frame 18 at the first connection positionCP1 and is connected to the column 14 at the second connection positionCP2. Then, the first connection position CP1 is higher than the secondconnection position CP2. For this reason, it is possible to performimaging at the first connection position CP1 higher than the secondconnection position CP2.

The position of the highest point in the elevation range of the frame 18can be higher than the first connection position CP1 by the height H asthe difference between the first connection position CP1 and the secondconnection position CP2. As a result, it is possible to suppress theheight of the column 14. Specifically, in a case where the position ofthe highest point in the elevation range of the frame 18 is 200 cm, andthe height H is 30 cm, the height of the column 14 can be made about 170cm. Then, it is possible to meet a height limit to the entrance or thelike of the imaging room, and to perform movement between rooms usingthe caster 16 without hindrance. In moving the apparatus body 11 usingthe casters 16, the frame 18 is moved down from the position of thehighest point in the elevation range.

As shown in FIG. 1 and the like, both the radiation source 20 and theradiation detector 21 protrude from the lower edge of the frame 18. Forthis reason, for example, it is possible to image a comparatively lowimaging part, such as a waist of the subject S in a sitting posture,without significantly moving down the frame 18.

The apparatus body 11 comprises the casters 16 for transport. For thisreason, it is possible to freely move the apparatus body 11. Theinstallation place of the apparatus body 11 is not limited to theimaging room, and may be carried and installed in a patient's room orthe like.

As shown in FIG. 6, the radiation source 20 emits the radiation R in aquadrangular pyramidal shape. For this reason, it is possible to finishimaging within a short time compared to a case where radiation R in afan shape is scanned in a height direction from a radiation source andis detected in a radiation detector with pixels disposed in aone-dimensional manner. Instead of the quadrangular pyramidal shape,radiation R in a conical shape may be emitted.

As shown in FIGS. 1 and 5, the subject S is positioned in the bore 19 inany posture of the upright posture and the sitting posture. For thisreason, it is possible to meet demands of a physician who wants toobserve a soft tissue, such as a lung, in a natural state with gravityor wants to observe a joint, such as a hip joint, in a state in which aload is applied with gravity.

The CT apparatus 10 comprises the radiation source 20 that emits theradiation R, the radiation detector 21 that detects the radiation R, theannular frame 18 that rotates the subject S positioned in the bore 19, aplurality of columns 14 that hold the frame 18 to be rotatable andmovable up and down in the vertical direction, the elevation mechanism40 that moves up and down the frame 18, and the rotation mechanism 50that rotates the frame 18. The radiation source 20 and the radiationdetector 21 are attached to the frame 18 at facing positions. As shownin FIG. 2, the frame 18 has the width W1 smaller than the width W2 ofthe radiation source 20 and the radiation detector 21 in the heightdirection over the whole periphery. As shown in FIG. 18, the imagingcontroller 77 performs control for operating the elevation mechanism 40in response to the return instruction 105 from the operator to move theframe 18 to the retreat height position set at the position of thehighest point in the elevation range of the frame 18 on the upper endside of the columns 14. The imaging controller 77 performs control foroperating the rotation mechanism 50 in response to the returninstruction 105 from the operator to rotate the frame 18 to the positionof 60° as the first rotation position where the radiation source 20overlaps the column 14A.

Since the frame 18 is rotated to the first rotation position where theradiation source 20 overlaps the column 14A, as shown in FIG. 11, whenthe subject S approaches inside the apparatus body 11 from between thecolumns 14A and 14C, the radiation source 20 does not obstruct subjectS. For this reason, there is no need to move up the frame 18 to aposition where the radiation source 20 exceeds the head of the subjectS. Accordingly, unlike the related art, there is no need to secure acomparatively large retreat space for retreating the frame 18 over thehead of the subject S in an upper portion of the apparatus body 11. Thatis, it is possible to make the apparatus body 11 compact in the heightdirection compared to the related art.

As shown in FIG. 14, the imaging controller 77 performs control foroperating the rotation mechanism 50 in response to the scout imaginginstruction 95 from the operator to move the frame 18 to the scoutimaging position for scout imaging before main imaging. The scoutimaging position is at least one of the second rotation position wherethe radiation source 20 confronts the subject S or the third rotationposition where the radiation source 20 faces the side surface of thesubject S. For this reason, it is possible to simply perform scoutimaging without troubling the operator so much.

As shown in FIGS. 16 and 17, the imaging controller 77 operates therotation mechanism 50 to rotate the frame 18 to the fourth rotationposition, and then, causes the radiation source 20 and the radiationdetector 21 to perform main imaging while rotating the frame 18 to thefifth rotation position. For this reason, it is possible to simplyperform main imaging without troubling the operator so much.

As shown in FIGS. 18 and 19, the imaging controller 77 operates therotation mechanism 50 to return the frame 18 from the fifth rotationposition to the first rotation position after main imaging. For thisreason, it is possible to simply return the frame 18 to the firstrotation position without troubling the operator so much.

In returning the frame 18 from the fifth rotation position to the firstrotation position, the imaging controller 77 rotates the frame 18 in adirection (in the example, the from the clockwise rotation direction CW)from the fifth rotation position toward the fourth rotation position.The direction from the fifth rotation position toward the fourthrotation position is opposite to a rotation direction (in the example,the counterclockwise rotation direction CCW) of the frame 18 in mainimaging. For this reason, the radiation source 20 and the radiationdetector 21 follows a trajectory of movement in main imaging withouthitting against the subject S. Accordingly, in a case where the subjectS keeps still, there is no concern that the radiation source 20 and theradiation detector 21 hit against the subject S, and it is possible tosecure the safety of the subject S.

In returning the frame 18 from the fifth rotation position to the firstrotation position, the imaging controller 77 rotates the frame 18 at thesecond set rotation speed, specifically, the double speed higher thanthe first set rotation speed from the fourth rotation position to thefifth rotation position. For this reason, it is possible to finish workfor returning the frame 18 from the fifth rotation position to the firstrotation position within a short time, and to reduce the stress of thesubject S who is waiting inside the apparatus body 11.

The columns are not limited to the straight shape shown in the drawing.As a column 110 shown in FIG. 23 as an example, in a case where theframe 18 is viewed from a direction in plan view, the column may have anarc shape following the frame 18. With such a shape, it is possible tofurther increase the strength of the column 110.

Although an aspect where both the radiation source 20 and the radiationdetector 21 protrude from the lower edge of the frame 18 has been shown,the technique of the present disclosure is not limited thereto. As shownin FIG. 24 as an example, an aspect where both the radiation source 20and the radiation detector 21 protrude from an upper edge of the frame18 may be made. Then, for example, it is possible to image acomparatively high imaging part, such as a head of the subject S in anupright posture, without significantly moving up the frame 18.

In an aspect shown in FIG. 24, the retreat height position is set to aposition shown in FIG. 25 as an example. In FIG. 25, the retreat heightposition is set on a lower end side of the column 14. In more detail,the retreat height position is a position of a lowest point in theelevation range of the frame 18. As described above, the position of thelowest point in the elevation range of the frame 18 is a position of asubstantially lower end of the column 14 and is a position where thefirst connecting part 43 is in contact with the front surface of thestage 13. In contrast with an aspect where both the radiation source 20and the radiation detector 21 protrude from the lower edge of the frame18, in the connecting member 17, the first connecting part 43 isdisposed downside, and the second connecting part 44 is disposed upside.In this case, the subject S approaches inside the apparatus body 11across the frame 18. Similarly to the arrow shown in FIG. 11, an arrowshown in FIG. 25 indicates a direction in which the subject S is ledinside the apparatus body 11.

As described above, the width W1 of the frame 18 in the height directionis smaller than the width W2 of the radiation source 20 and theradiation detector 21 in the height direction. For this reason, a burdenon the subject S is reduced compared to the related art in which animaging unit having the same width as the radiation source 20 and theradiation detector 21 is placed over the subject. Accordingly, it ispossible to allow the subject S to easily approach inside the apparatusbody 11 compared to the related art.

Although the position of 60° where the radiation source 20 overlaps thecolumn 14A has been shown as the first rotation position, the techniqueof the present disclosure is not limited thereto. A position of 300°where the radiation source 20 overlaps the column 14C may be set as thefirst rotation position. Alternatively, a position of 180° where theradiation source 20 overlaps the column 14B may be set as the firstrotation position, and the subject S may be allowed to approach insidethe apparatus body 11 from between the columns 14B and 14C.

A unit that overlaps the column 14 at the first rotation position is notlimited to the radiation source 20. The radiation detector 21 mayoverlap the column 14 at the first rotation position. A portion thatoverlaps the column 14 is not limited to the whole of the radiationsource 20 or the radiation detector 21, and at least one of at least apart of the radiation source 20 or at least a part of the radiationdetector 21 may overlap the column 14. For example, as shown in FIG. 26,a position of 90° where a right end portion of the radiation detector 21overlaps the column 14C may be set as the first rotation position.Similarly to the arrow shown in FIG. 12, an arrow shown in FIG. 26indicates a direction in which the subject S is let inside the apparatusbody 11.

The numbers of columns is not limited to three. As shown in FIG. 27 asan example, four columns 115A, 115B, 115C, and 115D may be disposed atpositions of 45°, 135°, 225°, and 315°. Even in this case, the center Cof the frame 18 falls within a quadrangle RA with the four columns 115Ato 115D as apexes. The column 115A is connected to the frame 18 througha connecting member 116A, and the column 115B is connected to the frame18 through a connecting member 116B. The column 115C is connected to theframe 18 through a connecting member 116C, and the column 115D isconnected to the frame 18 through a connecting member 116D. In thiscase, for example, a position of 45° where the radiation source 20overlaps the column 115A is set as the first rotation position, and thesubject S is allowed to approach inside the apparatus body 11 frombetween the columns 115A and 115D.

As shown in FIG. 28 as an example, columns 120A and 120B forreinforcement may be disposed at a position of 90° backward of thecolumn 14A and a position of 270° backward of the column 14C. Even inthis case, the center C of the frame 18 falls within a pentagon PA withthe five columns 14A to 14C, 120A, and 120B as apexes. The column 120Ais connected to the frame 18 through a connecting member 121A, and thecolumn 120B is connected to the frame 18 through a connecting member121B. In this case, for example, a position of 90° where the radiationsource 20 overlaps the column 120A, the right end portion of theradiation detector 21 overlaps the column 14C, and a central portion ofthe radiation detector 21 overlaps the column 120B is set as the firstrotation position, and the subject S is allowed to approach inside theapparatus body 11 from between the columns 14A and 14C.

As shown in FIG. 29 as an example, a pair of columns 125A and 125B maybe disposed at a position of 60°, a pair of columns 125C and 125D may bedisposed at a position of 180°, and a pair of columns 125E and 125F maybe disposed at a position of 300°. Even in this case, the center C ofthe frame 18 falls within a hexagon HA with the six columns 125A to 125Fas apexes. The columns 125A and 125B have a size substantially half ofthe column 14A, the columns 125C and 125D have a size substantially halfof the column 14B, and the columns 125E and 125F have a sizesubstantially half of the column 14C. The columns 125A and 125B areconnected to the frame 18 through a connecting member 126A, the columns125C and 125D are connected to the frame 18 through a connecting member126B, and the columns 125E and 125F are connected to the frame 18through a connecting member 126C. In this case, for example, a positionof 60° where the radiation source 20 overlaps the columns 125A and 125Bis set as the first rotation position, and the subject S is allowed toapproach inside the apparatus body 11 from between the columns 125A and125F. As will be understood from the examples of FIGS. 28 and 29, thearrangement of the columns may not be at regular intervals.

The elevation mechanism of the frame 18 is not limited to the ball screwmechanism shown in the drawing. An elevation mechanism 130 shown in FIG.30 as an example may be employed. In FIG. 30, the elevation mechanism130 is configured of a counterweight 131, a wire 132, and a pulley 133.The counterweight 131 has a weight required for balancing with the frame18 to which the radiation source 20 and the radiation detector 21 areattached. One end of the wire 132 is attached to the counterweight 131.The wire 132 is inserted into the top plate 15 and is wound on thepulley 133 provided on the front surface of the top plate 15. The wire132 is inserted into the top plate 15 again, and the other end thereofis attached to the frame 18. The frame 18 is moved up and down dependingon an operator's manual operation to move up and down.

In this way, in a case where the elevation mechanism 130 using thecounterweight 131 is used, the operator can set the position of theframe 18 depending on a sense of the hand of the operator. Both theelevation mechanism 40 of the ball screw mechanism and the elevationmechanism 130 using the counterweight 131 may be mounted in theapparatus body 11, and the elevation mechanism 40 and the elevationmechanism 130 may be switched by a clutch or the like.

The motor 52 for rotation may be configured of a stepping motor and arotation position of the frame 18 may be derived depending on the numberof pulses applied to the motor 52 for rotation. The frame 18 is notlimited to the annular shape, and may have a polygonal annular shape.

Although the CT apparatus 10 has been shown as the medical imagecapturing apparatus, the technique of the present disclosure is notlimited thereto. A simple radiography apparatus that captures aprojection image while changing an angle one by one may be employed. Aradiography apparatus that has a frame, to which two sets of radiationsource 20 and radiation detector 21 are attached, irradiates the subjectS with the radiation R simultaneously from the front surface and theside surface of the subject S to obtain two projection images, andchecks anatomical shapes of a hip joint and a spine of the subject S anda connection condition of a spine and a lower limb.

The hardware configuration of the computer configuring the controldevice 12 can be modified in various ways. For example, the controldevice 12 may be configured of a plurality of computers separated ashardware for the purpose of improving processing ability andreliability. For example, the functions of the reception unit 75 and theRW controller 76 and the functions of the imaging controller 77, theimage processing unit 78, and the display controller 79 may bedistributed to two computers. In this case, the control device 12 isconfigured of two computers.

In this way, the hardware configuration of the computer of the controldevice 12 can be appropriately changed depending on requiredperformance, such as processing ability, safety, or reliability. Notonly hardware but also an application program, such as the operationprogram 70, can be of course duplicated or distributed and stored in aplurality of storages for the purpose of securing safety andreliability.

In the above-described embodiment, for example, as the hardwarestructures of processing units that execute various kinds of processing,such as the reception unit 75, the RW controller 76, the imagingcontroller 77, the image processing unit 78, and the display controller79, various processors described below can be used. Various processorsinclude a programmable logic device (PLD) that is a processor capable ofchanging a circuit configuration after manufacture, such as a fieldprogrammable gate array (FPGA), and/or a dedicated electric circuit thatis a processor having a circuit configuration dedicatedly designed forexecuting specific processing, such as an application specificintegrated circuit (ASIC), in addition to the CPU 62 that is ageneral-purpose processor configured to execute software (operationprogram 70) to function as various processing units.

One processing unit may be configured of one of various processorsdescribed above or may be configured of a combination of two or moreprocessors (for example, a combination of a plurality of FPGAs and/or acombination of a CPU and an FPGA) of the same type or different types. Aplurality of processing units may be configured of one processor.

As an example where a plurality of processing units are configured ofone processor, first, as represented by a computer, such as a client ora server, there is a form in which one processor is configured of acombination of one or more CPUs and software and the processor functionsas a plurality of processing units. Secondly, as represented by systemon chip (SoC) or the like, there is a form in which a processor thatrealizes all functions of a system including a plurality of processingunits into one integrated circuit (IC) chip is used. In this way,various processing units may be configured using one or more processorsamong various processors described above as a hardware structure.

In addition, as the hardware structure of various processors, morespecifically, an electric circuit (circuitry), in which circuitelements, such as semiconductor elements, are combined, can be used.

The technique of the present disclosure can also be appropriatelycombined with various embodiments and/or various modification examplesdescribed above. The technique of the present disclosure is not limitedto the above-described embodiments, and various configurations can be ofcourse employed without departing from the spirit and scope of thetechnique of the present disclosure. In addition to the program, thetechnique of the present disclosure extends to a storage medium thatstores the program in a non-transitory manner. The content of the abovedescription and the content of the drawings are detailed description ofportions according to the technique of the present disclosure, and aremerely examples of the technique of the present disclosure. For example,the above description relating to configuration, function, operation,and advantageous effects is description relating to configuration,function, operation, and advantageous effects of the portions accordingto the technique of the present disclosure. Thus, it is needless to saythat unnecessary portions may be deleted, new elements may be added, orreplacement may be made to the content of the above description and thecontent of the drawings without departing from the gist of the techniqueof the present disclosure. Furthermore, to avoid confusion and tofacilitate understanding of the portions according to the technique ofthe present disclosure, description relating to common technicalknowledge and the like that does not require particular description toenable implementation of the technique of the present disclosure isomitted from the content of the above description and the content of thedrawings.

In the specification, “A and/or B” is synonymous with “at least one of Aor B”. That is, “A and/or B” may refer to A alone, B alone, or acombination of A and B. Furthermore, in the specification, a similarconcept to “A and/or B” applies to a case in which three or more mattersare expressed by linking the matters with “and/or”.

All cited documents, patent applications, and technical standardsdescribed in the specification are incorporated by reference in thespecification to the same extent as in a case where each individualcited document, patent application, or technical standard isspecifically and individually indicated to be incorporated by reference.

What is claimed is:
 1. A medical image capturing apparatus comprising: a radiation source that emits radiation; a radiation detector that detects the radiation, an annular frame to which the radiation source and the radiation detector are attached and in which a subject is positioned in a bore; and three or more columns that hold the frame to be movable up and down in a vertical direction.
 2. The medical image capturing apparatus according to claim 1, wherein, in a case where the frame is viewed in plan view and a polygon with the three or more columns as apexes is assumed, a center of the frame falls within the polygon.
 3. The medical image capturing apparatus according to claim 1, wherein the frame has an annular shape, and the columns hold the frame to be rotatable around the subject.
 4. The medical image capturing apparatus according to claim 3, wherein the three or more columns are disposed at regular intervals on the same periphery.
 5. The medical image capturing apparatus according to claim 3, wherein, in a case where the columns are viewed from a direction in which the frame is viewed in plan view, the columns are in an arc shape following a shape of the frame.
 6. The medical image capturing apparatus according to claim 1, wherein at least one of the three or more columns has an opening for allowing the subject to be visually recognized from an outside.
 7. The medical image capturing apparatus according to claim 1, wherein at least one of an input device or a display is attached to at least one of the three or more columns.
 8. The medical image capturing apparatus according to claim 7, wherein the column to which at least one of the input device or the display is attached has rigidity higher than other columns.
 9. The medical image capturing apparatus according to claim 1, further comprising: connecting members that are connected to the frame at a first connection position and are connected to the columns at a second connection position, wherein the first connection position is higher than the second connection position.
 10. The medical image capturing apparatus according to claim 1, wherein both the radiation source and the radiation detector protrude from any one of an upper edge or a lower edge of the frame.
 11. The medical image capturing apparatus according to claim 1, further comprising: casters for transport.
 12. The medical image capturing apparatus according to claim 1, wherein the radiation source emits the radiation having a pyramidal shape.
 13. The medical image capturing apparatus according to claim 1, wherein the subject is positioned in the bore in any one of an upright posture or a sitting posture. 